Main Navigation

Current page is: The Physical Site

The Physical Site

The UCR Botanic Gardens occupies 16 hectares (40 acres) of rugged,
hilly terrain along the eastern boundary of the U.C. Riverside campus,
in the foothills of the Box Springs Mountains. Natural features include
two prominent arroyos with steep slopes and intermittent water flow in
one - Chancellor's Canyon - and a spectacular assemblage of huge,
weathered granite boulders in the upper reaches of the other - Alder
Canyon. The elevation varies from 335 meters above sea level at the
entrance to 442 meters in the southeast corner of the Gardens (1100 to
1450 feet).

The annual rainfall in this area has averaged only 271 mm
(10.67 inches) over a 97-year period. From 1956 to 1986 the rainfall
exceeded the long term average only ten times. The majority of this
scant rainfall falls between November and May. With such low rainfall,
especially during the hottest time of the year, the Gardens needs to be
under irrigation most of the year to grow any but the most drought
tolerant plants.

From a horticultural perspective, the Gardens is in USDA Hardiness Zone 9 and Sunset Western Garden Book
Climate Zone 19. The combination of this local subtropical climate and
the irregular terrain produce a range of "microclimates" that allow a
surprising variety of plants to be grown. The cold-air-drained upper
elevations are nearly frost free, while the lower canyon bottoms are
likely to receive light frosts in winter. The average maximum
temperature for the year is 26 degrees C (78 degrees F) while the
average minimum is 10 degrees C (50 degrees F). Over a 59 year period,
Riverside averaged 14 days with a minimum below 0 degrees C (32 degrees
F) per year. Over a 12 year period, the number of days with a maximum
over 32 degrees C (90 degrees F) has been 59 per year.

About one-third of the Gardens' 40 acres remains unplanted.
This land consists of variably degraded Riverside Coastal Sage Scrub
Community and grassland. Common plants native to the site include brittlebush (Encelia farinosa), California buckwheat (Eriogonum fasciculatum), California sagebrush (Artemisia californica) and deerweed (Lotus scoparius).

Native Plants found at the UCR Botanic Gardens

Perennial Plants

Artemisia californica

California sagebrush

Baccharis salicifolius

Mule fat

Datura wrightii

Jimson Weed

Dichelostemma pulchellum

Blue dicks, wild hyacinth

Dudleya lanceolata

Live forever

Encelia farinosa

Brittlebush

Epilobium (Zauschneria) canum

California fuchsia

Eriogonum elongatum

Wild buckwheat

Eriogonum fasciculatum

California buckwheat

Galium angustifolium

Narrow-leaved bedstraw

Gutierrezia californica

California matchweed

Haplopappus (Ericameria) palmeri

Palmer's goldenbush

Lessingia filaginifolia

California-aster

Lotus scoparius

Deerweed

Marah macrocarpus

Wild cucumber

Melica imperfecta

Melic grass

Mimulus longiflorus

Monkeyflower

Mirabilis californica

Wishbone bush

Nothalaena newberryi

Cotton fern

Opuntia littoralis

Prickly pear

Opuntia parryi (O. californica)

Snake cholla, cane cholla

Phacelia ramosissima

Salvia mellifera

Black sage

Sambucus mexicana

Elderberry

Salvia apiana

White sage

Sarcostemma cynanchoides

Climbing milkweed

Scrophularia californica

California figwort

Solanum xantii

Purple nightshade

Annual Plants in Season

Amsinckia menziesii

Fiddleneck, rancher's fireweed

Antirrhinum nuttallianum

Calandrinia ciliata

Red maids

Camissonia bistorta

California sun cup

Camissonia micrantha

Crassula connata

Pygmy-weed

Cryptantha intermedia

Popcorn flower

Eucrypta chrysanthemifolia

Gilia angelensis

Lasthenia glabrata

Goldfields

Lotus strigosus

Lupinus truncatus

Collar lupine

Nemophila menziesii

Baby blue-eyes

Pectocarya penicillata

Phacelia distans

Phacelia minor

Wild Canterbury bells

Salvia columbariae

Chia

Tropidocarpum gracile

More Information

General Campus Information

University of California, Riverside900 University Ave.Riverside, CA92521
Tel: (951) 827-1012